You are probably also aware that the gospels were not all written at the same times or places and some of the letters to churches were written before the birth, ministry, & adventures of Jesus were even recorded. The Scripture Scout's Sleuth for the Truth calendar shows the chronological order as to when the books were written. The lesson plans are in chronological order as to when these historical events occurred, even though some have been tweaked by being put together with continuity of theme. Both are offered to the teacher, and thus, the students can get a 'big picture look at the book.' For example, Paul’s missionary travels seem all over the place in this chart because that's how he travelled! Galatians was the FIRST book written, and it was several years after the crucifixion of Christ, so we chose to keep some of the lessons from the epistles ordered by theme.